1. Technical Field
The present invention relates to a method of driving an electrophoretic display device, and also to an electrophoretic display device.
2. Related Art
Recently, flexible non-luminous display devices have been used as flexible display devices, such as electronic papers. One of such non-luminous display devices includes an electrophoretic display device that uses an electrophoresis phenomenon. Here, the electrophoresis phenomenon is a phenomenon that, for example, when an electric field is applied, fine particles move on the basis of Coulomb force in a disperse system in which fine particles (electrophoretic particles) are dispersed in liquid (disperse medium).
Then, the flexible electrophoretic display device often employs flexible organic thin film transistors (organic TFTs) as thin film transistors. That is, the electrophoretic display device is formed of, for example, an active matrix circuit that uses organic TFTs for pixel transistors.
Then, there has been proposed a manner in which the electrophoretic display device is formed of an active matrix circuit, which is described in JP-A-2002-169190. JP-A-2002-169190 describes that, in an electrophoretic display panel that includes a disperse system, in which electrophoretic particles are dispersed, between an element substrate and an opposite substrate, pixel electrodes, scanning lines, data lines and pixel TFTs are formed on the element substrate, and a common electrode is formed on the opposite substrate. In addition, in a process that is common to a process in which the pixel TFTs are formed on the element substrate, TFTs that constitute a scanning line driving circuit and a data line driving circuit are also formed. Thus, the low-cost active matrix electrophoretic display device is manufactured.
However, in the case of a sheet of paper, both the front and rear faces of the sheet of paper is usable; however, in the case of an electrophoretic display device, it has been usual that only the front face is used for display. Then, there has been proposed an electrophoretic display device that displays an image, or the like, on both the front and rear faces, which is described in JP-A-2005-321732. JP-A-2005-321732 describes that, on the front face of the display device, a first display portion having electrically charged particles is provided between a common substrate that has a common driving electrode layer and a first display substrate that has a first opposite electrode layer, which is a ground side electrode. In addition, on the back face of the image display device, a second display portion having electrically charged particles is provided between the common substrate that is shared with the front face and a second display substrate having a second opposite electrode layer, which is a ground side electrode. Then, by electrically switching between the first and second opposite electrode layers, an electric field is generated only on any one of the first and second display portions. Thus, individual images, or the like, are displayed respectively on the first and second display portions, so that it has been possible to display an image, or the like, on each of the front and rear faces of the electrophoretic display device.
JP-A-2005-321732 achieves front and rear double-side display by sharing the common driving electrode layer between the first and second display portions; however, the opposite electrode and the electrophoretic display layer need to be provided for each of the display portions and, therefore, it has been difficult to form a thin electrophoretic display device and/or to reduce manufacturing costs.